1. Field of the Invention
This invention relates to a seal for a valve and more particularly to a seal which is integral with a wrap-around liner that surrounds the rotor in a multiported rotary type valve.
2. Description of the Prior Art
Rotary type valves (also commonly known as plug valves) have a relative simple design since they require only a housing, a rotor contained within the housing, and a means for rotating the rotor relative to the housing so as to align the rotor bore with the ports contained within the housing. This simple design, however, involves a complex sealing problem between the rotor and the housing. The prior art uses various approaches to minimize the leakage between the rotor and the housing such as precision machining the mating surfaces of the rotor and the housing to ensure a tight fit therebetween. Such precision machining is very expensive and the resulting close tolerances on the mating surfaces cannot be held because of wear with continued use of the valve. An alternate approach is to fit O-rings into complex machined dovetail grooves within the rotor. Here again, the machining required is expensive and there is the possibility of an omitted or pinched O-ring during assembly.
Because of the wide applicability of rotary type valves and their inherent sealing problems, it has become desirable to develop a positive means for sealing these valves which is relatively inexpensive and does not require precision machining.